The present invention pertains to wheelchairs and particularly to suspension of the large rear wheels of wheelchairs which are manually operable.
In the typical manual wheelchair each rear wheel is a large wheel mounted to the frame of the wheelchair without any provision for absorption of shocks or damping of vibration of the wheelchair. In such a wheelchair, shocks and vibrations arising from irregularities and defects in the traveled surface are transmitted through the rear wheels to the wheelchair occupant. These shocks and vibrations contribute to spasms and back pain in wheelchair users. Studies have shown that low back pain is a common problem among people with disabilities who use wheelchairs.
One attempt to reduce shocks and vibrations to wheelchair users is shown in U.S. Pat. No. 4,455,031 wherein a shock absorber interconnects the seat of the wheelchair with a frame on which the large rear wheels are mounted. My U.S. Pat. No. 7,032,917 issued Apr. 25, 2006 discloses a solution to shock absorption in which separate suspension devices interconnect the rear wheel hubs to side frame members of the wheelchair frame. Additional solutions reducing vibration and shock to the body of wheelchair users are desirable.